What is the most likely diagnosis

A 23 years old man was admitted with severe vomiting abdominal pain, and hypervantilation, following vigorous exercise BP :- 90 / 50, ECG , HR 80 / min, multiple ectopic beats, Na+ 127, K+ 5.2, Cl- 79, HCO3- 20 PO2, PCO2, Glucose :- normal What is the most likely diagnosis    
Source: Doc2Doc BMJ Cardiology - Category: Cardiology Authors: Source Type: forums